556 
5 J6 
py 1 



TREASURY DEPARTMENT 
UNITED STATES PUBLIC HEALTH SERVICE 

HUGH S. GUMMING, Surgeon General 



THE 

GROWTH-PROMOTING PROPERTIES 

OF MILK AND DRIED-MILK 

PREPARATIONS 



BY 

J. M. JOHNSON 

chemist 

Division of Pharmacology , Hygienic Laboratory 

United States Public Health Service 



REPRINT No. 690 

FROM THE 

PUBLIC HEALTH REPORTS 

August 26, 1921 

(Pages 2044-2057) 



2. 1 « ? So ^ 5^ ^' 




WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1921 



Ij 

Monograph 



ADDITIONAL COPIES 

OF THIS PUBLICATION MAY BE PROCURED FROM 

THE SUPERINTENDENT OF DOCUMENTS 

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AT 

5 CENTS PER COPY 



LIBRARY OF CONGRESS 

OCT 281921 






THE GROWTH-PROMOTING PROPERTIES OF MILK AND 
DRIED-MILK PREPARATIONS. ^ 

By J. M. Johnson, Cl)emist, Division of Pharmacology, Hygienic Laboratory, United States Public Health 

Service. 

Numerous investigators have studied the effect of milk upon 
growth. Janet Lane-Claypon ^ found practically no difference 
between boiled and raw milk when fed with bread to growing albino 
rats. F. G. Hopkins ^ observed that when rats are fed upon a well- 
balanced diet of purified foodstuffs, furnishing all the necessary 
elements except the growth-promoting accessories, which, as shown 
by control experiments, did not permit normal growth, the addi- 
tion of very small amounts of fresh milk, from 1 to 3 or 4 per 
cent of the total solids of the food, gave immediate and good growth. 

Osborne and Mendel,* however, found that in feeding fresh milk 
to rats as the sole source of water-soluble vitamine, at least 16 c. c. 
daily were required to give normal growth, and sometimes even that 
amount failed. 

G. Winfield ' found that 87 infants fed upon dried whole milk, 
compared with infants fed upon the breast, did not grow as well as 
the latter at first, but later made approximately normal or even 
better growth. Experiments upon 40 rats fed upon dried whole 
milk only, showed that normal health was maintained for a period 
of 16 months or more, but growth fell below normal when one-half 
to two-thirds of adult weight was reached. Osborne and Mendel ' 
found that it was necessary to use at least 24 per cent dried whole 
milk in making up a food mixture which would give normal growth 
to rats. 

The object in the experiments carried out by the author of this 
paper was to compare raw and pasteurized cow's milk with that 
obtained by addition of the required amount of water and butter 
fat to skim milk powder, so-called "reconstructed" milk. This milk 
has come into use in certain places where there is a scarcity of dairy 
herds. Under normal conditions it can not be produced more 
economically than fresh milk; but where transportation for great 
distances enters into the equation, because of the fact that 87 per 
cent water must be carried with fresh milk, it pays to consider 
"reconstructed" milk. Therefore, the question comes up wh^her 

1 Reprint from the Pubiic Health Reports, vol. 36, No. 34, Aug. 26, 1921, pp. 2044-2057. 

2Jour. Hyg. (1909J, IX, 233. 

sjour. Physiol. (1912), XLIV, 42.5. 

<Jouf. Biol. Chem. (1918), XXXTV, 537. 

6 Brit. Local Govt. Board Food Rep. (1918), XXIV, 139-56. 

^ Loc. cit. 

67778°— 21 S 



4 MILK AND DRIED-MILK PREPARATIONS. 

it is safe to allow this milk to be sold where the public will place the 
same reliance upon it as upon fresh milk as a food for children or 
adults. 

MILKS STUDIED. 

1. Reconstructed milk made from skim milk powder by the 
addition of butter and water. The skim milk powder was obtained 
from a factory using the spray method of drying. For a good part 
of the time of the experiment this milk was secured from a restaurant 
conducted under the auspices of the United States War Department, 
where the milk powder, water, and butter were mixed in a machine 
especially devised for this purpose. During the other part of the 
experiment the milk was made up in the Laboratory so as to approxi- 
mate the composition of standard pasteurized milk with 3.5 per cent 
butter fat. 

2. Raw milk obtained from the dairy of the United States Depart- 
ment of Agriculture. 

3. Raw certified milk obtained from a local dairy. 

4. Pasteurized milk obtained from another local dairy. 

5. A few experiments were also carried out with a mixture of skim 
milk powder and a basal diet. 

METHOD OF FEEDING. 

Healthy young white rats weighing 40 to 60 grams were selected 
and kept in individual cages. The food intake was accurately con- 
trolled. The animals were kept supplied with fresh water. Body 
weight was taken twice a week. The food was made up as follows: 
A basal mixture was made of starch, 48 per cent; casein, 25 per 
cent; Osborne and Mendel's'' salt mixture, 5 per cent; lard, 10 per 
cent; unsalted butter, 10 per cent; powdered agar, 2 per cent. 
The casein in this mixture was washed free of water-soluble vitamine 
with dilute acetic acid, followed by washing with water many times, 
and was dried and ground before using. Ten per cent of butter was 
selected in order to give the animals an excess of fat-soluble vitamine, 
since the experiments dealt only with a comparison of water-soluble 
vitamine in the milks. In the making of reconstructed milk, butter 
is used; therefore a study of its fat-soluble vitamine content was 
unnecessary. 

The diets fed to the rats were made up fresh each day by the 
addition of measured portions of the milk with a weighed portion of 
the basal mixture. No control experiments were run upon the basal 
mixture alone, but proof was obtained that it contained no growth- 
promoting accessories by the experiments with small amounts of 
milk mixed with it, when all the animals failed to grow. The animals 
were given each day slightly more food than they would eat. This 
caused a moderate variation in the food consumption of rats on the 
same diet. 

' Jour. Biol. Chem. (1917), XXXII, 317. 



MILK AND DRIED- MILK PREPARATIONS. 



5 



In order to be sure that there was no appreciable difference 
between the chemical composition of these various milks, chemical 
analyses were made at frequent intervals during the progress of the 
experiment. Averages are given for the month in each case. 
Although the results of the chemical analyses show that there is 
quite a marked variation of the fat and total solids content, I do not 
think that the difference is great enough to cause an appreciable 
change in the concentration of the water-soluble vitamine. 

Table I. — Average ckeviical com/position ofmilks.^ 



Month. 


Total 
solids. 


Fat. 


Solids 
not fat. 


Protein. 


Ash. 


Milk. 


1919. 
June 


12.48 
13.38 
12.81 

13. 19 
12. 63 
12.86 
13.40 
12. 77 

14. 38 
11.98 

15. 40 
12.10 
1-i. SI 
12. 43 

13.86 
12.83 
35.26 


4.01 
3.73 
4.33 

4.09 

4.10 

4.12 

4.83 

4.07 

5.74 

3.72 

6.5 

3.65 

5.9 

3.68 

.5.2 

3.65 

6.93 

5.1 

4.2 

7.48 

CO 

4.3 

3.5 

4.33 

4.8 

3.1 


8.47 
9.58 
8.48 
9.10 
8.53 
8.74 
8.57 
8.70 
8.63 
8.26 
8.65 
8.46 
8.30 
8.75 

S.63 
9.18 
8.32 


3.16 
3. .58 
3.11 
3.36 
3.17 
3.05 
3.28 
3.12 
3.42 
2.94 
3.31 
3.11 
3.30 
3.21 

3.3' 
3.50 
3.2C 


0.541 
.64 
.55 
..59 
.55 
.61 


Agricultural Department. 


Do 


July 


Agricultural Department. 


Do 


August 


Agricultural Department. 


Do 


September 


Agricultural Department. 


Do 




October 




Agrlcultiual Department. 


Do 




November 




Agricultiual Department. 


Do 




December 




Agricultural Department. 


Do 




1920. 
January 




Agricultural Department. 


Do 




February 




Agricultural Department. 


Do 






Do 










Local pasteurized. 
Agricultural Department. 


March 


15.62 


8.14 


3.14 




Do 




April 


12.73 


8.39 


3.12 




Agricultural Department. 


Do 




May 


12.88 


8.55 


3.15 




Agricultiual Department. 


Do 




Do 








Local pasteurized. 


1 









I The chemical analyses of the milks were carried out by various members of the division ol chemistry 
of the Hygienic Laboratory, most of them by Mr. O. H. Schunk and Mr. C. G. Remsburg. 



Table II gives the various diets fed. 

Table II. — Diets fed. 



Diet 
No. 


Amount 
of basal 


Amount of milk. 


Diet 
No. 


Amount 
of basal 


Amount of milk. 


mixture. 




mixture. 




IV 


100 


25 Agricultural Department 


V 


100 


100 reconstructed. 






plus 25 water. 


X 


100 


200 reconstructed. 


m 


100 


50 Agricultural Department 


XIII 


100 


250 reconstructed. 






plus 50 water. 


XIV 


100 


.300 reconstructed. 


n 


100 


25 Agiicultural Department 


XVI 


100 


350 reconstructed. 






plus 75 water. 


XXII 


100 


200 local pasteurized. 


I 


100 


100 Agricultural Department. 


XX 


100 


250 local pasteurized. 


VIII 


100 


150 Agricultural Department. 


XVII 


100 


300 local pasteurized. 


IX 


100 


200 Agricultural Department. 


XVIII 


100 


350 local pasteurized. 


XI 


100 


250 Agricultural Department. 


XXI 


100 


250 local certified. 


XII 


100 


300 Agricultural Department. 


XIX 


100 


300 local certified. 


XV 


100 


350 Agricultural Department. 


XXIII 


100 


31.2 grams spray process skim 


VII 


100 


50 reconstructed plus 50 water. 






milk powder. 


VI 


100 


75 reconstructed plus 25 water. 









MILK AND DRIED-MILK PREPARATIONS. 



Table III gives the results of the experiments carried out with 
the diets composed of basal mixture plus Agricultural Department 
raw milk. In some cases where the rat failed to show good growth, 
small amounts of yeast were given in order to supply additional 
water-soluble vitamine. This usually caused improvement. This 
addition of yeast is not shown in the tables, but will be found indicated 
in the charts at the end of the article. 

Table III. — Summary of experiments on rats fed on Agricultural Department vnll , 



Num- 
ber 
of 
rat. 



26o' 

27 9 

28 cT 

29 9 
329 
33 cf 

17 cJ 

239 

239 

249 

24 9 

99 

Hd' 

12 9 

13,^ 

149 

15 9 

169 

19 

19 

BcT 

3c? 

49 

49 

5(? 

5cr 

7<? 

7<? 

89 

89 

102 J' 

103 9 

104 9 

84 c? 

85 c? 
869 
87 c? 
889 

53 9 

54 c? 

55 d' 
569 
57 c? 
589 
59 9 
779 



Diet 
fed. 



IV.. 
IV.. 
IV.. 
IV.. 
IV.. 
IV.. 
III.. 
IX.. 
III.. 
IX.. 
III.. 
IX.. 
II... 
II... 
II... 
II... 
II... 
II... 
II... 
I.... 
VIII 
I.... 
VIII 

I.... 

VIII 

I.... 

VIII 

I.... 

VIII 

I.... 

VIII 
IX.. 
IX.. 
IX.. 
XL. 
XI.. 
XI.. 
XI.. 
XI.. 
XII. 
XII. 
XII. 
XII. 
XV. 
XV. 
XV. 
XV. 











Average 


c. c. of 










i lilk consumed | 








Dura- 


daily. 




Initial 
weight. 


Maxi- 
mum 
weight. 


Final 
weight. 


tion of 
e-xperi- 
nient 






Number. 










in days. 


of days 
weighed. 


C.c. 


Grams. 


Grams. 


Gram.?. 








66 


125 


104 


149 


All. 


1.5 


63 


133 


130 


149 


All. 


1.5 


43 


108 


69 


137 


All 


1.1 


61 


113 


109 


149 


All. 


1.4 


47 


100 


82 


149 


All. 


1.1 


54 


137 


123 


149 


All. 


1.5 


63 


80 


78 


39 


.All. 


2.7 


78 


153 


142 


104 


All. 


10.8 


50 


71 


71 


39 


All. 


2.8 


71 


129 


124 


104 


All. 


9.7 


64 


71 


68 


39 


All. 


2.6 


68 


136 


121 


104 


All. 


9.2 


53 


100 


86 


133 


All. 


3.9 


73 


180 


178 


149 


All. 


5.8 


42 


110 


104 


133 


All. 


3.9 


80 


244 


226 


149 


All. 


6.1 


57 


97 


91 


133 


All. 


3 3 


64 


142 


141 


133 


All. 


4.3 


56 


103 


101 


133 


All. 


3.4 


47 


58 


58 


39 


All. 


4.5 


58 


69 


43 


68 


All. 


4.3 


55 


77 


74 


39 


All. 


4.7 


74 


140 


135 


104 


All. 


8.6 


62 


94 


94 


39 


All. 


6.2 


94 


140 


140 


94 


All. 


9.3 


58 


119 


119 


39 


All. 


7.0 


119 


182 


166 


101 


All. 


10.9 


62 


117 


115 


39 


All. 


7.0 


115 


195 


187 


104 


All. 


9.7 


67 


95 


88 


39 


All. 


5.9 


88 


110 


100 


94 


All. 


6.1 


88 


210 


205 


157 


45 


13.0 


78 


150 


150 


180 


49 


11.4 


75 


188 


188 


180 


48 


14.5 


47 


220 


202 


198 


62 


17.4 


49 


281 


284 


198 


64 


20.0 


44 


224 


203 


198 


61 


IS.l 


47 


283 


286 


198 


61 


21.5 


43 


211 


211 


198 


61 


16.0 


46 


165 


158 


209 


sr. 


17.7 


62 


295 


295 


209 


39 


22.9 


58 


270 


270 


209 


35 


23.1 


56 


182 


182 


209 


35 


19.9 


77 


237 


232 


253 


64 


22.5 


53 


200 


200 


209 


35 


24.2 


52 


203 


203 


209 


35 


21.5 


46 


187 


180 


212 


53 


15.9 



Remarks. 



Discharged. 

Do. 
Died. 
Discharged. 

Do. 

Do. 
Changed to IX. 
Discharged. 
Changed to IX. 
Discharged. 
Changed to IX. 
Discharged. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 
Changed to VIII. 
Died. 

Changed to VIII. 
Dis( harged. 
Changed to XIII. 
Discharged. 
Changed to VIII. 
Discharged. 
Changed to VIII. 
DiS' harged. 
Changed to VIII. 
Discharged. 
Died. 
Discharged. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 
Accident; died. 



It is seen from Table III that a food mixture consisting of purified 
foodstuffs plus milk as the sole source of water-soluble vitamine must 
contain at least 2^ parts of milk to 1 part of the basal ration in 



MILK AND DRIED-MILK PREPARATIONS. 7 

order to produce normal growth. Since a full-grown male rat 
weighs about 280-300 grams, and a full-grown female about 180 
grams, a rat upon such a diet consumes just about 16-18 cubic 
centimeters of milk daily. These figures agree with those of Osborne 
and Mendel.^ It is also seen that the rate of growth of rats receiving 
less than 2h parts of milk in their diet was accelerated after increasing 
the amount of milk in the diet. 

The results obtained with reconstructed milk (Table IV) show 
that here again normal growth was not attained until the milk mix- 
ture was composed of at least 2^ parts of milk to 1 part of basal 
ration. 

Table IV. — Summary of experiments on rats fed on reconstructed milk. 



Num- 
ber of 
rat. 


Diet fed. 


Initial 
weight. 


Maxi- 
mum 
weight. 


Final 
weight. 


Dura- 
tion of 
experi- 
ment in 

days. 


Average c. c. of 
mi lie consumed 
daily. 


Remarks. 




Number 
of days 
weighed. 


Co. 




44 9 
459 


VII 


Grams. 
39 
35 
48 
30 
33 
51 
34 
48 
48 
62 
30 
39 
38 
49 
44 
75 
41 
55 
54 
40 
45 
58 
62 
47 
45 
64 
46 
40 


Grams. 

87 

95 
100 
139 

71 
100 
101 
149 
104 
145 

91 
100 
157 
168 
154 
" 230 

72 
197 
205 
187 
168 
297 
254 
232 
182 
281 
195 
216 


Grams. 

81 

92 

87 

139 

67 

100 

52 

135 

94 

130 

62 

97 

157 

152 

149 

230 

50 

192 

200 

187 

165 

297 

252 

164 

182 

281 

194 

216 


116 
116 
116 
131 
116 
116 
106 
126 
116 
116 
101 
116 
342 
320 
240 
246 
40 
198 
198 
198 
198 
209 
266 
146 
209 
208 
208 
208 


All. 

All. 

All. 

All. 

All. 

All. 

Ail. 

All. 

All. 

All. 

All. 

All. 

All. 

All. 

All. 

All. 
21 
58 
53 
57 
50 
32 
64 
94 
31 
30 
29 
28 


1.8 

1.9 

2.2 

2.4 

2.8 

3.6 

3.1 

4.5 

3.3 

6.4 

. 3.9 

4.0 

11.4 

9.1 

10.7 

1,3.4 

7.6 

14.8 

16.1 

14.2 

12.2 

22.6 

15.1 

17.9 

18.1 

25.7 

19.1 

24.0 


Discharged. 

Do. 

Do. 

Do. 

Do. 

Do. 
Died. 
Discharged. 

Do. 

Do. 
Died. 
DL<!charged. 

Do. 

Do. 

Do. 

Do. 
Died. 
Discharged. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do 




VII 




479 


VII 




48 c? 


VII 




399 
409 
419 

42 <? 

43 9 
35 c? 
369 
37 cf 
499 
509 
519 
529 

1159 


VI 




VI 




VI 




VI . . 




VI 




V... . .. 




V 




V... 




X 




X 




X 




X . 




X 




899 


xrri 




909 


xin 




919 


xrii 




929 
61c? 
62 c? 
113c? 
639 
64 c? 
659 
66 1? 


XIIl 




XIV 




XIV 




XIV 




XV^I 




XVI 




XVI 




XVI 









• Loc. cit. 



8 



MILK AND DRIED-MILK PREPARATIONS. 



The results on pasteurized milk (Table V) again show that not 
until the food mixture is composed of at least 2^ parts of milk to 1 
part of basal ration is there normal growth obtained. 

Table V. — Summary of experiments on rats fed on pasteurized milk. 



Num- 


Diet fed. 


Initial 
weight. 


Maxi- 
mum 
weight. 


Final 
weight. 


Dura- 
tion of 
experi- 
ment in 

days. 


Average c. c. of 
milk consumed 
daily. 


Remarks. 


rat. 


Number 

of days 

weighed. 


C.c. 


1059 

107 9 

108 J 


XXII 


Grams. 
38 
59 
45 
40 
40 
45 
60 
41 
32 
55 
43 
45 
45 
30 
47 
76 


Grams. 
154 
160 
127 
162 
275 
227 
227 
213 
207 
260 
305 
240 
193 
221 
203 
185 


Grains. 
152 
151 
99 
160 
275 
227 
227 
213 
207 
260 
302 
240 
187 
221 
203 
184 


180 
163 

73 
126 
198 
198 
198 
208 
208 
198 
208 
208 
208 
208 

89 
175 


57 
59 
8 
86 
70 
67 
67 
29 
39 
74 
36 
37 
36 
36 

«77 


11.6 
10.9 
7.1 
16.2 
21.3 
19.2 
16.3 
21.1 
19.3 
20.6 
19.3 
26.6 
21.4 
22.6 


Discharged. 


XXII 


Do. 


XXII 


Died. 


1149 
94 c? 


XXII 


Discharged. 


XX 


Do. 


95 (? 


XX 


Do. 


96 (? 


XX 


Do. 


679 
699 
101c? 


XVII 


Do. 


XVII 


Do. 


XVII 


Do. 


70 (? 


XVII 


Do. 


71 d- 
729 
739 
749 
1069 


XVIII 

XVIII 

XVIII 

xvni 

XVIII 


Do. 
Do. 
Do. 

Unknown. 


23.9 


Discharged. 



1 Accident; died. 

The results on certified milk (Table VI) are in accord with those 
found in the other milks; that is, that it is necessary to use 2^ parts 
of milk to 1 part of basal mixture to give a ration that will produce 
full growth in rats. 

Table VI. — Summary of experiments on rats fed on local certified milk. 



Num- 
ber of 
rat. 



Diet fed. 



Initial 
weight. 


Maxi- 
mum 
weight. 


Final 
weight. 


Dura- 
tion of 
experi- 
ment in 

days. 


Average c. e. of 
milk consumed 
daily. 


Number 
of days 
weighed. 


c.c. 


Grams. 


Grams. 


Grams. 








52 


190 


190 


198 


71 


15.5 


44 


187 


187 


198 


66 


16.7 


54 


207 


205 


198 


63 


18.6 


67 


297 


294 


178 


66 


19.4 


47 


315 


315 


70 


66 


27.4 


36 


285 


285 


70 


66 


25.8 


40 


270 


270 


91 


66 


23.0 


38 


180 


180 


98 


66 


20.2 


42 


185 


185 


70 


66 


19.8 


43 


235 


230 


98 


66 


21.4 


45 


189 


185 


91 


66 


19.3 


37 


195 


184 


216 


74 


18.2 


50 


197 


188 


203 


64 


22.4 


42 


260 


258 


216 


75 


21.7 


54 


247 


214 


235 


65 


18.6 


59 


185 


170 


216 


75 


15.2 



Remarks. 



979 
989 
999 

100 <? 

117c? 

118c? 

119 c? 

1209 

1219 

122 c? 

123 9 
799 
809 
81 (? 
829 
839 



XXI 
XXI 
XXI 
XXI 
XXI 
XXI 
XXI 
XXI 
XXI 
XXI 
XXI 
XIX 
XIX 
XIX 
XIX 
XIX 



Discharged. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 



Table VII gives the results obtained on feeding a dry mixture of 
the basal ration plus skim milk powder. 



MILK AND DRIED-MILK PREPARATIONS. 



Table VII. — Summary of experiments on rats fed on spray process skim-milk powder plus 

basal mixture. 


Num- 
ber 


Diet fed. 


Initial 
weight. 


Maxi- 
mum 
weight. 


Final 
weight. 


Duration 
of experi- 
ment 
in days. 


Average grams of 
milk powder con- 
sumed daily. 


Remarks. 


rat. 


Days 
weighed. 


Grams. 




109 c? 
llOcf 
lllcf 
1129 


XXIII 

XXIII 

XXUI 

XXIII 


Grams. 
46 
45 
54 
53 


GTama. 
2S0 
240 
204 
185 


Grams. 
270 
234 
190 

178 


165 
150 
165 
153 


97 
94 
99 

97 


2.6 
2.4 
2.5 
2.5 


Discharged. 
Do. 
Do. 
Do. 



Zoo 



2oo 



too 




Chart 1.— Showing unsatisfactory growth of albino rats on diets low in raw milk. Addition of yeast 
resulted in increased growth. (Arrows indicate period of yeast feeding.) 

Diet: IV. 100 grams basal, 25 c. c. Agr. Dept. raw milk, 75 c. c. water. 




Chart 2.— Showing unsatisfactory growth of albino rats on diets low in milk: no diflerence betweenraw 
and reconstructed milks. Increase of milk in diet caused increased growth (17, 23, 24). 

Diets: 

III. 100 grams basal, 50 c. c. Agr. Dept. raw milk, 50 e. c. H2O. 

IX. 100 grams basal, 200 c. c. Agr. Dept. raw milk. 

VTI. 100 grams basal, .50 c. c. reconstructed milk, 50 c. c. H5O. 



10 



MILK AND DRIED-MILK PREPARATIONS. 




MILK AND DRIED-MILK PREPARATIONS. 



11 



Diet XXIII was so mixed as to give in terms of liquid milk the same 
ratio as three and one-half times as much milk as basal ration. By 
the use of this diet it was possible to determine whether the subnormal 
growth observed in rats receiving 3^ parts of liquid milk to 1 part of 
basal ration was due to an insufficient consumption of solids on 
account of the excessive water content of such mixtures. The above 
mixture also contains approximately 24 per cent skim milk powder. 



3CO 



lOOf 




-Showing unsatisfactory grovvtii oi albino laLs on diets low in milk; raw milk is no betterthan 
reconstructed milk. 

Diets: 

I. 100 grams basal, 100 c. c. Agr. Dept. raw milk. 
VIII. 100 grams basal, 150 c. c. Agr. Dept. raw milk, 
v. 100 grams basal, 100 c. c. reconstructed milk. 

All except one of the animals upon this diet attained full growth. 
Osborne and Mendel ^ had previously found that 24 per cent was 
the minimum for whole milk powders in such a mixture to promote 
growth. These figures of 24 per cent whole milk powder are far in 
excess of their figures of 16 c. c. daily per animal, going upon the 
average daily consumption of food by a growing rat. 

Charts I-IX give in graphic form the results of the same experi- 
ments as shown in the tables. Normal curves are taken from 
"The Rat," by Henry H. Donaldson, 1915, and are begun at 40 gm. 
body weight. 

SUMMARY. 

1. Reconstructed milk made from skim milk powder (spray proc- 
cess), water, and butter fat contains growth-promoting properties for 
albino rats equal to those of fresh and pasteurized milk; that is to 

'Loc. cit. 



12 



MILK AND DBIED-MILK PREPAHATIONS. 




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MILK AND DRIED-MILK PREPARATIONS. 



15 




16 



MILK AND DRIED-MILK PREPARATIONS. 



say, the process of drying skim milk by the spray process does not 
injure the water-soluble vitamine. 

2. In feeding albino rats a basal mixture of purified foodstuffs plus 
milk of any kind, it is necessary to give at least 2^ parts of milk to 
1 part of the basal mixture in order to promote normal growth. This 
is confirmatory of Osborne and Mendel, who found that 16 c. c. of 
fresh milk daily is required by a growing albino rat. 




Chart 9.— Showing good growth of albino rats on a diet composed of dry basal mixture and dry skim milk 
powder. This gave about 24 per cent of milt powder. 

Diet: XXIII. 100 grams basal, 31.2 grams spray process skim milk powder, fed dry. 
Y, Birth of young. 

3. An excessive amount of liquid milk furnished to albino rats gives 
subnormal growth after a time, because of the large amount of liquid 
in proportion to the solids in such a diet. 

ACKNOWLEDGMENTS. 

The author takes this opportunity of expressing his thanks to Dr. 
Carl Voegtlin, Chief of the Division of Pharmacology, under whose 
direction this work was carried out, and who aided in many ways 
during its progress. Thanks are also due to Mr. J. W. Thompson, who 
rendered material assistance in the work. 



o 



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